The present invention relates to a protective shell of a tool battery for a hand-held tool battery having a tool battery housing. The present invention also relates to a hand-held tool battery.
Hand-held tool batteries serve to supply a hand-held machine tool, in particular a jackhammer or a combination hammer with an electric supply current. Protective shells of tool batteries, which are essentially known from the prior art, serve to protect hand-held tool batteries from external environmental influences such as for example dust, moisture, and impacts.
The object of the present invention is to indicate a protective shell of a tool battery and a hand-held tool battery, which provide improved protection against influences or are better protected from such.
With regard to the protective shell of a tool battery, the object is achieved by the protective shell of a tool battery being formed in a sandwich construction with an outer shell and an intermediate layer acting as a damping layer, the intermediate layer being configured softer and/or more elastic than the outer shell, and the intermediate layer being arranged on the outer shell in such a way that it is situated between the outer shell and a surface of the tool battery housing when the protective shell of a tool battery is arranged on the tool battery housing.
The invention includes the knowledge that when a hand-held tool battery received in a hand-held machine tool falls on the ground unprotected, it may result in the tool battery housing breaking. This applies all the more so for large and heavy batteries, i.e., in particular for hand-held tool batteries with 22 volts or 36 volts supply voltage. Protective shells of tool batteries of the prior art are typically very bulky and heavy and thus solve the problem of break protection in a very user-unfriendly manner.
Since the protective shell of a tool battery according to the invention is formed in a sandwich construction with an outer shell and an intermediate layer acting as a damping layer, and the intermediate layer is softer and/or more elastic than the outer shell, local tension concentrations or tension peaks, which typically occur when the hand-held tool battery impacts on a hard surface, are distributed over a larger surface and thus the probability of the tool battery housing breaking is minimized. Advantageously, the protective shell of a tool battery according to the invention can be implemented in a comparatively thin and lightweight manner, which is particularly user-friendly. Moreover, it has been recognized that a deformation of the tool battery housing caused by a fall is particularly effectively prevented and thus an input of impact energy into the battery cells, which are accommodated in the tool battery housing, can be reduced. Moreover, the outer shell of the protective shell of a tool battery provides increased wear resistance in comparison to protective shells of tool batteries of the prior art since the outer shell can be designed comparatively rigidly.
In a particularly preferred configuration, the outer shell comprises an outer shell elasticity modulus and the intermediate layer comprises an intermediate layer elasticity modulus, and the outer shell elasticity modulus is larger than the intermediate layer elasticity modulus. The measurement of the elasticity modulus can be determined in compliance with EN ISO 527-1 (European standard for plastic for determining the tensile properties). The outer shell of the protective shell of a tool battery can for example have an elasticity modulus greater than 1500 MPA (mega pascal), preferably greater than 2000 MPA. The outer shell of the protective shell of a tool battery preferably consists of plastic. It can, for example, consist of shock-resistant polystyrene with an elasticity modulus greater than 1500 MPA, preferably greater than 2000 MPA.
The intermediate layer acting as a damping layer preferably consists of plastic. The intermediate layer acting as a damping layer preferably comprises an elasticity modulus of less than 2000 MPA, preferably less than 1500 MPA, further preferably less than 1000 MPA or 500 MPA. It has been found to be advantageous when the intermediate layer consists of an elastomer, in particular a thermoplastic elastomer.
The outer shell and the intermediate layer can consist of the same material and comprise thicknesses that are different to each other. This has the advantage that only one material group has to be provided which favors affordable production of the protective shell of a tool battery. The intermediate layer preferably consists of a foamed plastic. The intermediate layer can consist of a thermoplastic elastomer, which is compact or foamed. The intermediate layer can consist of compact or foamed nitrile rubber or synthetic rubber. It has been found to be advantageous when the intermediate layer consists of polystyrene.
It has also been found to be advantageous when the outer shell has higher shore hardness than the intermediate layer. Shore hardness is determined according to DIN ISO 7619-1. The outer shell can thus, for example, have hardness greater than 80 shore A and the intermediate layer a hardness less than 80 shore A, preferably less than 70 shore A or 60 shore A.
In order to further minimize a reduction of tension peaks caused by impact, the sandwich construction preferably comprises an additional shell and an additional intermediate layer. The additional shell and/or the additional intermediate layer can be arranged in relation to the outer shell in such a way that they are situated between the outer shell and the surface of the tool battery housing. Additional shells and further intermediate layers are preferably alternated with each other. A respective additional intermediate layer particularly preferably has an intermediate layer elasticity modulus and an additional shell has an outer shell elasticity modulus, and the intermediate layer elasticity modulus is less than the outer shell elasticity modulus.
It has been found to be advantageous when the outer shell and the additional shell consist of the same material. It has been found to be advantageous when the intermediate layer and the additional intermediate layer consist of the same material.
The intermediate layer can have a wall thickness of between 0.5 mm and 10 mm, preferably of between 2 mm and 2.5 mm. The outer shell preferably has a wall thickness of between 0.5 mm and 10 mm, preferably of between 2 mm and 2.5 mm. In the context of simple producibility, it has been found to be advantageous when the intermediate layer has a substantially constant wall thickness. Alternatively, the wall thickness of the intermediate layer can vary. It has been found to be advantageous when the wall thickness of the intermediate layers scales with the impact direction relative to the center of gravity position of the tool battery on which the protective shell of a tool battery is to be applied. In other words, the wall thickness of the intermediate layer is designed with a higher wall thickness than in other regions at the point where the tool battery housing typically contacts the ground during a fall.
In a particularly preferred configuration, an overall wall thickness of the protective shell of a tool battery is less than 10 mm, preferably independent of the number of intermediate layers and/or shells encompassed by it. In other words, an outer shell, a first intermediate layer, an intermediate layer, and an additional intermediate layer can, for example, be provided, whose (summary) overall wall thickness is less than 10 mm. An overall wall thickness of the protective shell of a tool battery can preferably be between 4 and 5 mm. It has been found that this constitutes an optimum between material usage and impact resistance in typical construction site situations.
The protective shell of a tool battery can be formed so that it can be fastened by means of an adhesive connection to the tool battery housing. Alternatively or additionally, the protective shell of a tool battery can be fastenable by means of a snap-in connection to the tool battery housing. It has been found to be advantageous when the protective shell of a tool battery can be or is fastened on the tool battery housing by means of a film hinge, which preferably cooperates with the snap-in connection.
The protective shell of a tool battery can particularly favorably be produced when the outer shell and/or the intermediate layer are formed on the tool battery housing by means of an injection molding process, in particular by means of co-injection.
It has been found to be advantageous when the protective shell of a tool battery is formed as a corner protector and/or edge protector for a tool battery. The protective shell of a tool battery is preferably formed to precisely receive a corner and/or an edge of the tool battery housing and to leave a predominate portion of the surface of the tool battery housing uncovered. The protective shell of a tool battery can be formed in such a way that it completely encloses precisely two corners and the edge delimited by these two corners.
With regard to the hand-held tool battery, the object is achieved by a hand-held tool battery with a previously-described protective shell of a tool battery, which is configured to be fastenable or is fastened to the tool battery housing.
Additional advantages emerge from the following description of the figures. Different exemplary embodiments of the present invention are represented in the figures. The figures, the description, and the claims include numerous features in combination. The person skilled in the art will expediently also consider the features individually and combine them to form reasonable additional combinations.
Identical and similar components are labelled with the same reference numerals in the figures.